changing the timing belt???

[White_Beast98]

Does the 1990 305 TBI timing belt ever need to be changed out since it is chain driven??? of corse if it broke but if it isn't starting right after checking and changing the battery and changing the starter and terminal cable what else could I check??? I am far from an expert but I am in the process. I need some wise knowledge sprinkled from some masters of the camaro engine.

[silicon212]

Originally Posted by White_Beast98

Does the 1990 305 TBI timing belt ever need to be changed out since it is chain driven??? of corse if it broke but if it isn't starting right after checking and changing the battery and changing the starter and terminal cable what else could I check??? I am far from an expert but I am in the process. I need some wise knowledge sprinkled from some masters of the camaro engine.

The 305, as with any Chevy V-8, does not use a timing belt. It does use a timing chain, and many (most) of these came from the factory driving a cam sprocket made out of aluminum and the teeth coated with nylon, to quiet the drive down. Over the years, the nylon will become brittle and crack. The chain will also stretch, exacerbating the problem by beating at and causing the nylon to break off, not to mention messing up the valve timing. Once the nylon strips off (and winds up in the oil pan sump), the aluminum teeth aren't up to the task of dealing with the steel chain, so they strip in short order. End of timing set - the cam stops turning and the engine stops running. This is usually how these fail. When this happens, the engine will sound "weird" when you try to turn it over, and if you take the cap off the distributor you will notice the rotor isn't turning with the cranking of the engine. Sometimes you get a warning that this is about to happen by the presence of a "knock", which sounds like a rod knock, coming from the FRONT of the engine.

There are far more common causes of the engine failing to start, however. The most common non-start maladies have to do with either a malfunction in the fuel delivery system or the ignition system, so check those first.

[CamaroRScrazy]

Does that mean you need to change the timing chain every say 100,000 miles or keep using until it has some symptoms?

Thanks.

Originally Posted by silicon212

The 305, as with any Chevy V-8, does not use a timing belt. It does use a timing chain, and many (most) of these came from the factory driving a cam sprocket made out of aluminum and the teeth coated with nylon, to quiet the drive down. Over the years, the nylon will become brittle and crack. The chain will also stretch, exacerbating the problem by beating at and causing the nylon to break off, not to mention messing up the valve timing. Once the nylon strips off (and winds up in the oil pan sump), the aluminum teeth aren't up to the task of dealing with the steel chain, so they strip in short order. End of timing set - the cam stops turning and the engine stops running. This is usually how these fail. When this happens, the engine will sound "weird" when you try to turn it over, and if you take the cap off the distributor you will notice the rotor isn't turning with the cranking of the engine. Sometimes you get a warning that this is about to happen by the presence of a "knock", which sounds like a rod knock, coming from the FRONT of the engine.

There are far more common causes of the engine failing to start, however. The most common non-start maladies have to do with either a malfunction in the fuel delivery system or the ignition system, so check those first.

[malletslinger]

Change it...even if there aren't obvious symptoms, it does greatly affect the engines performance, economy, drivability, etc... I HIGHLY RECOMMEND THIS EVEN IF YOUR SPROCKETS DON'T INCORPORATE THE NYLON DESIGN.
My 89 V6 didn't really show symptoms, but when I went to replace it myself, I found the old guid was BADLY worn and the rubber was even broken in some places, and the chain was sagging big time! The only reason I thought of replacing it in the first place was that the vibrating at stops was driving me nuts and replacing the chain will help with that.
The difference in the way the engine ran was unbelievable.

[Blue Bowtie]

Most of the nylon-toothed cam sprockets were gone from inventory by 1987. I haven't seen a roller-cammed SBC engine with one. The trucks after 1987 may still have had them, however. If you use good lubricants and change them with adequate frequency, the timing set can outlast the engine. I know of one that has 325K on it. The V-6s are a different story.

[Blue Bowtie]

Silicon,

Did your '88 have a nylon cam sprocket? Does it have factory rollers? I'm confused...

[silicon212]

Originally Posted by Blue Bowtie

Silicon,

Did your '88 have a nylon cam sprocket? Does it have factory rollers? I'm confused...

No, it had a steel sprocket on it. The last nylon-sprocketed Chevy I had was an '85 350 - the very block that is in my car now (before it was rebuilt).

As for factory rollers - original engine, yes ... current engine, no.

What I find funny about the block in my car is that it's an '85, with the two-piece rear seal, yet it is machined for a factory roller cam - it has the three bolt bosses in the intake valley machined and drilled and tapped for bolts, plus the front of the block under the timing sprocket is also machined and drilled for the lock plate. The block is a 4-bolt out of a 1/2 ton truck. It strikes me as odd because I wasn't aware of any Chevy getting factory rollers until 1987.

[wrightz28]

With the General being notably trying to keep things cheap on the production end, and the LB9 and L98 TPI motors being introduced in '85, I wouldn't be suprised if all the blocks past a certain point in the produciton year were machined to go wither way